The present invention relates to a runflat tire system, more particularly to a support ring mounted on a wheel rim to support the inside of the tread portion of the deflated tire.
Heretofore, various runflat tire systems by which, even if the tire goes flat, it is possible to travel for a practical long distance have been proposed. For example, the Japanese patent application publication NOS. 8-504389 (WO 94/13498 A1), 10-6721 (U.S. Pat. No. 5,891,279 A), 2001-354002 (U.S. Pat. No 6,415,839 B1) and 2003-502200 (WO 00/76791 A1) disclose such techniques, and nowadays, the runflat distance reaches to several hundred kilometers even under a relatively high running speed of up to about 80 km/hr. However, when seeking such a long runflat distance, not a little increase in the vehicles' wheel weight was inevitable because an increase in the material thick is necessary in order to increase the durability and strength.
Therefore, the inventors made a study on the shape or configuration of the support ring which can derive maximum durability and thus maximum runflat distance therefrom using a minimum material to reduce the wheel weight, and it was discovered that, by providing a radially-extending load-supporting wall with a special configuration, the buckling strength thereof is remarkably increased.